Conventional AC generators for vehicles are each equipped with a frame one end of which has an end wall and with a rectifier. The rectifier is composed of a substantially U-shaped cooling fin extending in parallel to the surface direction of the end wall and of a plurality of diodes for a number of, for example, three phase windings of a stator; these plurality of diodes are separately mounted on the cooling fin.
An example of a frame of such an AC generator is disclosed in U.S. Pat. No. 6,198,188 B1, which was filed by the same applicant as the present invention, corresponding to Japanese Unexamined Patent Publication No. 2000-253625.
Referring to FIG. 11, one end wall 101 of a frame 100 of an AC generator continues from an annular side wall thereof, and a tubular boss 105 having a cylindrical side wall extends from the periphery of a hole H thereof in an axial direction of a rotary shaft rotatably supported in the hole H.
Four spokes 106 are radially arranged at intervals and configured to join the tubular boss 105 to the outer ring portion 104.
Four fin supports 103 are formed on the outer ring portion 104 of the end wall 101 of the frame 100. A female screw hole 102 is so formed through each of the fin supports 103 as to align with a corresponding one of through holes (not shown). The through holes are formed through an outer periphery of a negative cooling fin.
Specifically, four screw bolts (not shown) are inserted in the respective through holes of the negative cooling fin to extend therefrom. The extending portions of the screw bolts are inserted in the corresponding female screw holes 102 to, be engaged therewith, respectively. This allows the negative cooling fin of the rectifier to be fastened to the frame 100.
The four fin supports 103 are configured to have a predetermined radially and circumferentially extending surface and axially project toward the negative cooling fin.
Four intake windows 107 are formed between the circumferentially adjacent four spokes 106, respectively. Four through holes 108 are formed through the outer ring portion 104 and arranged radially outwardly adjacent to the radial outer edges of the four spokes 106, respectively.
A plurality of negative diodes are fitted in respective fitting holes of the negative cooling fin. Diode leads, such as negative main terminals, extending from the respective negative diodes in an axial direction of the rotary shaft are joined to AC (Alternative Current) terminals of terminal blocks; these AC terminals are joined to stator leads extending from the three-phase windings of a stator of the AC generator.
On the other hand, in order to reduce the resistance of one or more phase windings, such as three-phase windings, constituting a stator coil of an AC generator, a stator coil with a specific structure is illustrated in U.S. Pat. No. 6,333,573 B1, which was filed by the same applicant as the present invention, corresponding to Japanese Patent Publication No. 3508687.
In the structure of the stator coil, each of three-phase stator windings is made up of a plurality of conductor segments each having a substantially rectangular shape in its lateral cross section. The plurality of conductor segments are inserted in slots of a stator.
One end of each of the conductor segments projecting one of the slots is sequentially welded to the other end of a corresponding one of the conductor segments projecting a corresponding another one of the slots so that the sequentially joined conductor segments provide radially layered annular windings. The configuration of each of the multiphase windings allows low resistance of the three-phase stator windings, thus improving a power output of the AC generator.